摘要:

We have made the first measurements of the imaging performance of a normal incidence soft x‐ray telescope at BK&agr; (0.183 keV, 67.6 A˚). The performance is quite good; at 1.5° off axis the resolution is about 1 arcsec full width at half‐maximum and 50% of the reflected power within 512 arcsec is contained within a diameter of 5 arcsec.

ISSN:0003-6951    

DOI:10.1063/1.92905

出版商:AIP    

年代:1982

数据来源: AIP

摘要:

A surface acoustic wave (SAW) delay line is demonstrated which is variable and employs interaction between the SAW on a piezoelectric substrate and an adjacent electrically conductive film. With this structure, a tunability of 2.7×10−3has been achieved by electrically controlling an air gap between a gold film and a (YZ)LiNbO3substrate. Improvements in the air‐gap fabrication techniques could increase the tunability up to ∼10−2.

ISSN:0003-6951    

DOI:10.1063/1.92906

出版商:AIP    

年代:1982

数据来源: AIP

摘要:

The efficient generation of continuous surface acoustic waves (SAW) by focusing the radiation of a synchronously pumped mode‐locked cw dye laser (mode‐locking frequency 76.44 MHz) on the surface of aYZLiNbO3crystal is reported. The surface acoustic waves were generated on a small absorbing surface area under varying excitation conditions and detected piezoelectrically by means of a narrowband interdigital SAW transducer, which yielded a voltage responsivity of 1.5 &mgr;V/mW cw laser power. The detected electrical signal verified the expected square law dependence of the acoustic power on the incident laser power.

ISSN:0003-6951    

DOI:10.1063/1.92907

出版商:AIP    

年代:1982

数据来源: AIP

摘要:

Soft x rays (100–10 000 eV), due to their short wavelength (0.1–10 nm) can play an important role in high resolution microscopy and lithography. The gas puffZpinch is an intense source of soft x rays. Calorimeter and x ray diode measurements showed that 10% of the stored electrical energy was converted to radiation in the range of 1–10 nm. Commercial photoresist polymethyl methacrylate (PMMA) and some new resists—CR 39, nitrocellulose, were exposed to the pinch radiation. The developed images on the resists have been studied with a scanning electron microscope. The resolution was found to be source limited, but a simple modification can improve the resolution by more than an order of magnitude.

ISSN:0003-6951    

DOI:10.1063/1.92908

出版商:AIP    

年代:1982

数据来源: AIP

摘要:

It is shown that an electrical discharge can dissociate the higher‐order sulfur molecules S3→8into dimers S2and thus create the proper environment for efficient conversion of XeCl radiation at 308 nm to the blue‐green. The use of a heat‐pipe configuration greatly alleviates the technological problems.

ISSN:0003-6951    

DOI:10.1063/1.92909

出版商:AIP    

年代:1982

数据来源: AIP

摘要:

The first superlattice avalanche photodiode (APD) is reported. The high field region of thisp‐i‐nstructure consists of 50 alternating Al0.45Ga0.55As (550 A˚) and GaAs (450 A˚) layers. A large ionization rate ratio has been measured in the field range (2.1–2.7)×105V/cm, with &agr;/&bgr;≃10 at a gain of 10 giving a McIntyre noise factorFn= 3. The ionization rate ratio enhancement with respect to bulk GaAs and AlGaAs is attributed to the large difference in the band edge discontinuities for electrons and holes at the heterojunction interfaces. The superlattice APD is a new device concept which can be used to develop low noise APD’s in a variety of III‐V materials including long wavelength 1.3–1.6‐&mgr;m semiconductors.

ISSN:0003-6951    

DOI:10.1063/1.92910

出版商:AIP    

年代:1982

数据来源: AIP

摘要:

Micro‐ and millisecond laser annealing of ZnTe monocrystals in a controlled atmosphere shows clearly that oxygen diffuses from an oxygen‐rich atmosphere into ZnTe. In the photoluminescence spectra, the typical red oxygen band is observed after annealing. At 2.360 eV, the intense luminescence line from an exciton bound to a Frenkel pair (VZn,Znint) is found.

ISSN:0003-6951    

DOI:10.1063/1.92911

出版商:AIP    

年代:1982

数据来源: AIP

摘要:

Mechanism of open‐circuit voltage enhancement in Au thin oxide‐n‐GaAs (1¯1¯1¯) solar cells prepared by room‐temperature wet oxidation has been studied. In contrast to earlier published results on (100) GaAs, barrier heights for metal‐insulator‐semiconductor and metal‐semiconductor cells are found to be the same, indicating absence of charge in the oxide or significant modification of surface states. It is shown that the increase in open‐circuit voltage is mainly caused by suppression of the majority‐carrier current due to tunneling through the oxide.

ISSN:0003-6951    

DOI:10.1063/1.92912

出版商:AIP    

年代:1982

数据来源: AIP

摘要:

We show that the electrical compensation of undoped GaAs grown by the liquid encapsulated Czochralski technique is controlled by the melt stoichiometry. The concentration of the deep donor EL2 in the crystal depends on the As concentration in the melt, increasing from about 5×1015cm−3to 1.7×1016cm−3as the As atom fraction increases from 0.48 to 0.51. Furthermore, we show that the free‐carrier concentration of semi‐insulating GaAs is determined by the relative concentrations of EL2 and carbon acceptors. As a result, semi‐insulating material can be obtained only above a critical As concentration (0.475‐atom fraction in our material) where the concentration of EL2 is sufficient to compensate residual acceptors. Below the critical As concentration the material isptype due to excess acceptors.

ISSN:0003-6951    

DOI:10.1063/1.92913

出版商:AIP    

年代:1982

数据来源: AIP

摘要:

A physical theory using a charge scattering model is proposed to interpret the experimental data of grain boundary transport in polycrystalline semiconductors. The calculated result explains the need of an attenuation factor as an added coefficient in the thermionic emission current.

ISSN:0003-6951    

DOI:10.1063/1.92914

出版商:AIP    

年代:1982

数据来源: AIP